Daniel Lemire's blog

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Science and Technology links (April 13th, 2018)

  1. Somewhat depressingly, there is very little evidence that you can improve people’s overall cognitive abilities:

Although cognitive ability correlates with domain-specific skills—for example, smarter people are more likely to be stronger chess players and better musicians—there is little evidence that chess or music instruction makes people smarter. Rather, smarter individuals are more likely to engage and excel in these fields.

That is, if you receive musical training, you may get better at playing an instrument. However, this will not make you better at programming in Java. Time spent in school does not significantly improves students’ cognitive skills. However, smarter people spend more time in school.

This failure to increase overall cognitive skills destroys one of the main premise of schooling. It also means that if you have kids, you should not push them into classes in the hope of making them smarter.

The same works at the scale of countries. Richer countries educate their people more… but it is not the added education that makes them richer.

Of course, you can make yourself smarter. Just buy a computer.

  1. A woman’s voice changes after pregnancy. It sounds more masculine, for a time at least.
  2. Women (>45 years old) who consume high-fat dairy products gain less weight over time.
  3. The youngest children in a school class are more likely than their classmates to receive pharmacological treatment for attention deficit/hyperactivity disorder (ADHD). This result suggests that it may be difficult to differentiate immaturity from ADHD.
  4. There are contradictory reports as to whether human beings create new neurons throughout their life. The LA Times has a nice article on neurogenesis: Scientists find signs of new brain cells in adults as old as 79.
  5. In small monkeys, eating less is strongly associated with a longer and healthier life according to a study published in Nature:

Compared to control animals, caloric restriction extended lifespan by 50% (from 6.4 to 9.6 years, median survival), reduced aging-associated diseases and preserved loss of brain white matter in several brain regions.

Importantly, this means that aging can be manipulated far more easily than might have been thought. That caloric restriction prolongs life and health has deep consequences. It means that your body does not age because it lacks energy or entropy. It also means that your body does not try to maximize your healthspan and lifespan.

It is unknown whether caloric restriction has the same effect on human beings. For the record, I do not practice caloric restriction. I eat all the time. I am, however, quite thin and small.

  1. Unsurprisingly, late-life depression is associated with an increased risk for all-cause dementia, vascular dementia and Alzheimer’s disease. This is yet more evidence that we need to take depression seriously. It is not normal to be depressed beyond a certain point.
  2. Kell and Pretorius have published a speculative article where they suggest that many diseases of old age (Alzheimer’s, Parkinson’s, atherosclerosis, arthritis) could be due to dormant microbes that “wake up” later in life, in part due to iron dysregulation. This is not a new theory, but this paper is well written and under open access. If you like this theory, you might like Mangan’s book: Dumping Iron. He believes that many of us have too much iron in our bodies. There are two main ways to reduce your iron store: chelation therapy (using drugs) or bleeding out.

It seems probably that iron dysregulation is real. Sadly, there is weak evidence that you can prevent it. The risk of Parkinson’s disease was higher among men who reported recent multiple blood donations and total iron intake was not associated with an increased risk of Parkinson’s disease. The trouble is that iron can take many forms and can go to different places in your body.